DE1175250B - Process for the preparation of 4, 5, 6-trichloro-7-hydroxyphthalane - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Boarding school Class: C07d

German KL: 12q-24

Number: 1175 250

File number: R 31647 IVb / 12 q

Filing date: December 8, 1961

Opening day: August 6, 1964

It is known that in the Diels-Alder addition from tetrachlorfuran to 2,5-dihydrofuran the ^, oJ-TetrachloMJ-endoxo- ^ S ^ -tetrahydrophthalan forms (see. German Patent 1,027,461).

The investigation showed that this addition product is a mixture of an endo and exo form represents the following constitution:

Cl

CI

F. 103 to 104 ⁰ C

Cl

F. 105 to 106 ^° C

Process for the preparation of 4,5,6-trichloro-7-hydroxyphthalane

It has also been proposed to employ a mixture of endo- and exo-form of 4,5,6,7-tetrachloro-4,7-endoxo-4,7,8,9-tetrahydrophthalans at 100 to 180 ⁰ C under a pressure to treat from 5 to 50 atm with 30 to 39% hydrochloric acid, the 4,5,6-trichloro-7-hydroxyphthalane being obtained in very good yield. The reaction product is contaminated by a low content of dark-colored by-products which have to be separated off in order to obtain a pure product. Furthermore, the reaction can only be carried out in hydrochloric acid-resistant pressure vessels, such as glass, enamel, tantalum or Teflon-lined autoclaves.

It has now been found that 4,5,6-trichloro-7-hydroxyphthalane quantitatively obtained by referring to a mixture of the endo- and exo-form des 4,5,6,7 - tetrachloro - 4,7 - endoxo - 4,7,8,9 - tetrahydrophthalans at -15 to -35 ° C with stirring at least as long as 90 to 98% sulfuric acid is allowed to act until a homogeneous solution is formed Applicant.

Ruhrchemie Aktiengesellschaft,

Oberhausen (Rhld.) - Holten

Named as inventor:
Dr. Hans Feichtinger, Dinslaken,
Dr. Hanswerner Linden,
Oberhausen (Rhld.) - Holten

the resulting reaction mixture the resulting ^, oJ-tetrachlor - ^ - dihydroxy- ^ S ^ -tetrahydrophthalan isolated and then allowed to stand at room temperature for 12 to 24 hours.

The reaction is suitably carried by dissolving the starting material in the 90 to 98% sulfuric acid and the mixture is stirred for several hours at -15 to -35 ⁰ C. The reaction solution, which has become homogeneous, is then diluted with ice, the sulfuric acid solution is extracted with ether below 10 ° C., the ether extract is neutralized by treatment with sodium bicarbonate solution, dried with calcined sodium sulphate, filtered and concentrated. The residue obtained is 4,5,6,7-tetrachloro-4,7-dihydroxy-4,7,8,9-tetrahydrophthalan as a colorless, unstable oil. When it is then left to stand for 12 to 24 hours at room temperature, the 4,5,6,7-tetrachloro-4,7-dihydroxy-4,7,8,9-tetrahydrophthalane, which is due to the geminal arrangement of a hydroxyl group and a chlorine atom, is converted the carbon atom in the 4- and 7-position is unstable, with release of 1 mol each of water and hydrogen chloride with aromatization into 4,5,6-trichloro-7-hydroxyphthalane. This stage is quantitative.

409 639/412

The reaction is illustrated by the following reaction scheme.

H ₂ SO ₄

-15 to -35 ° C

~ Cl Cl OH \ \ , H _A O T / CLL ^ / HO Cl

- H ₂ O; - HC 1 Cl

The course of the reaction occurring in the second process stage also takes place when the ^, oJ-TetrachloMJ-dihydroxy ^ j ^^ - tetrahydrophthalan is still dissolved in the organic solvent. For example, the ethereal solution becomes after 12 to 24 hours standing at room temperature the 4,5,6 - trichloro - 7 - hydroxyphthalane obtained by evaporation.

The process product can be used directly as a fungicidal active ingredient or for organic syntheses will.

example

In an open 250 cc Erlenmeyer flask were with good stirring by means of a magnetic stirrer in 100 ecm 98% sulfuric acid, which by means of a Ethanol-carbon dioxide cold bath was kept at -20 to 25 ° C, 27.6 g (0.10 mol) of finely powdered Mixture of the endo and exo forms of 4,5,6,7-tetrachloro-4,7-endoxo-4,7,8,9-tetrahydrophthalane (M.p. 68 to 98 ° C) given. After stirring for about 1 hour a colorless, homogeneous solution was formed. To complete the reaction, the Leave the mixture at the specified temperature for a further 2 hours with further stirring. then the reaction mixture was crushed ice

ίο given and the sulfuric acid mixture with ether extracted. The ether extract was then dried over calcined sodium sulfate, filtered and concentrated. 29.4 g of 4,5,6,7-tetrachloro-4,7-dihydroxy-4,7,8,9-tetrahydrophthalane were obtained as water-white

15 colorless oil (chlorine content calculated 48.24%, found 47.98%). The oil was allowed to stand for 24 hours at room temperature, wherein j sam with elimination of hydrogen chloride and water long-OH _n a white crystalline substance converted,

which had a temperature of 215 to 222 ° C after washing with water. By a single recrystallization from ethyl acetate, 23.7 g of 4,5,6-trichloro-7-hydroxyphthalan was obtained, melting at 227.5 to 228.0 ⁰ C. The yield was 99% of theory.

Claims (1)

Claim: A process for the preparation of 4,5,6-trichloro-7-hydroxyphthalane, characterized in that a mixture of the endo and exo form of 4,5,6,7 - tetrachloro - 4,7 - endoxo - 4, 7, 8,9-tetrahydrophthalane at -15 to -35 ⁰ C with stirring at least as long as 90 to 98 percent sulfuric acid is allowed to act until a homogeneous solution is formed, the resulting 4,5,6,7-tetrachlor from the resulting reaction mixture - 4,7 - dihydroxy - 4,7,8,9 - tetrahydrophthalan isolated and then allowed to stand for 12 to 24 hours at room temperature. 409 639/412 7.64 © Bundesdruckerei Berlin